1. Field of the Invention
The present invention relates to an apparatus and method for the manufacture of fiber reinforced structures. More specifically, the present invention relates to an apparatus and method of use of a remotely actuated, localized pressure and heat apparatus for the consolidation, curing and bonding of fiber elements in structures.
2. State of the Art
It is desirable to have inexpensive, strong, lightweight, easily manufactured components in a variety of sizes and geometries for use in aerospace and aircraft applications. Composite reinforced, or xe2x80x9cstiffenedxe2x80x9d, structures, such as shells, fuel tanks, fuselage panels, wing skins, etc., provide recognized advantages in aerospace applications over conventional metal assemblies, typically of aluminum, titanium, or combinations thereof, in terms of relatively lower weight, higher strength, and stiffness for the composite structures. The acceptance of all-composite structures has been hampered by the lack of demonstrated, repeatable, and inexpensive fabrication methodology and apparatus, particularly where a large reinforced composite structure is desired, as a suitable autoclave may not be available for the curing of the fiber elements forming the structure. In simple terms, the structure may be too large for any known existing autoclave for curing or may not be capable of transport to a suitable autoclave for curing. Thus, many such structures are Limited to high-performance, military, and/or aerospace applications, as not being cost-competitive in other applications.
A composite shell structure may require discrete internal or external reinforcing elements or stiffeners and bulkheads, hereinafter referred to generally as xe2x80x9cribsxe2x80x9d and xe2x80x9cbulkheads,xe2x80x9d adjacent a continuous shell structure, to provide enhanced stiffness to the shell structure in terms of torsional and bending resistance. The larger the composite shell structure and the greater the stresses and the more severe the operating environment, the greater the need for such reinforcement. Reinforcing elements may be discrete and remote from each other, maybe disposed in a mutually parallel relationship, or may be disposed an intersecting relationship to define the reinforcing required for the composite structure. In some instances, the reinforcement ribs and bulkheads for the structure may be formed in segments and subsequently joined at intersection points to form the reinforcement for the composite structure prior to the formation of the continuous shell therewith. Such is particularly advantageous where the composite structure is large, requiring substantial reinforcement ribs and bulkheads and having complex geometric shapes, either for the ribs and bulkheads or the overall structural shape.
The ribs and bulkheads for the reinforcement of the composite structure are typically formed of xe2x80x9ccomposite fiber elementsxe2x80x9d or xe2x80x9cfiber elementsxe2x80x9d including carbon fiber impregnated or coated with a curable bonding agent. By way of example and not Limitation, composite fibers may include elongated filaments of glass, graphite, boron, or polyarimid (Kevlar(trademark)), as specifications indicate.
While components of the ribs and bulkheads may be formed individually, it is necessary to subsequently assemble the rib and bulkhead components into a completed reinforcing structure for the application of the continuous shell of composite material thereto. To assemble and cure the individual rib and bulkhead components to form the completed reinforcing structure, an apparatus and method is required for the clamping and curing of the fiber elements of the rib and bulkhead components locally, particularly at the joints between adjacent ribs and bulkheads.
The present invention relates to an apparatus and method for the manufacture of fiber reinforced structures. The present invention is directed to an apparatus and method for the use of a remotely actuated localized pressure and heat tool for the consolidation, curing and bonding of portions of fiber elements in composite structures. The apparatus of the present invention comprises an apparatus including members for clamping the desired portion of the fiber elements to be joined, pressure members, and/or heat members. The method of the present invention is directed to the application and use of the clamping apparatus.